1. Field of the Invention
This invention relates to the initial installation and subsequent maintenance of deadfront electrical distribution junctions in grade level junction enclosures and specifically to a mounting plate for the deadfront grade level electrical enclosure and a method of making the mounting plate.
2. Prior Art Statement
In an electrical distribution system, especially in a residential or light industrial environment, a junction enclosure is utilized to provide security, environmental protection, a physical safety bather and a stable mounting for subsequent electrical service junction switching and maintenance operations. A typical junction enclosure is provided with a transitional mounting plate secured to the inside surface of the back panel of the enclosure. The mounting plate is subsequently field configured for the intended installation. At the time of configuration, the typical mounting plate must be removed from the junction enclosure, configured by installing a junction module thereto with up to three junction mounting straps, six bolts, lock washers and nuts and thereafter remounted to the back panel of the junction enclosure.
It is known to provide a rigidly bolted junction mounting plate for an electrical junction enclosure wherein the mounting plate is supplied with four or more threaded fasteners to secure the mounting plate to the back panel of the junction enclosure. For instance, see the SFGD Pad Mounted Sectionalizing Equipment manufactured by Shallbetter, Inc., 3110 Progress Drive, Oshkosh, Wis. 54901 or the Safefront Pad Mounted Outdoor Enclosures manufactured by Elliott Industries, Inc., PO Box 6388, Bossier City, La. 71171-6388 USA. There are slots, holes, or a combination thereof in the mounting plate for various configurations of junctions. The parking stand is produced separately and welded to the mounting plate for the use of portable feed-thru and standoff bushing devices for field switching and maintenance. A threaded insert is welded to the plate to accommodate tank grounding connectors. At assembly of junctions to a rigidly bolted mounting plate, the following steps are required:                1. Remove four or more fasteners from studs protruding from the back panel of the enclosure to release the mounting plate from the enclosure.        2. Remove the mounting plate from the enclosure.        3. Assemble junction straps to the junction.        4. Assemble lock washers to mounting bolts.        5. Hold the junction in place on the mounting plate while holding the mounting plate separate from the enclosure.        6. Install mounting bolts with lock washers in turn onto the junction straps and install nuts on the mounting bolts.        7. Tighten all nuts on the junction mounting bolts.        8. Install assembled mounting plate to enclosure.        9. Install fasteners to studs projecting from the back panel of the enclosure.        10. Tighten fasteners to studs to fasten the mounting plate to the enclosure.        11. Install ground wire to the threaded insert on the mounting plate.        12. Install ground wire to the enclosure.        13. Install elbows and cables to junctions.        14. Energize the junctions in the enclosure.        
This lengthy and difficult procedure is exacerbated by requiring the line person to hold onto the ten pound mounting plate while assembling components thereto. Additionally, the enclosure fasteners are often misplaced or lost. Removal and reinstallation of junctions to a rigidly bolted mounting plate requires the additional steps of prior to step 1 above though step 12 is omitted:                15. De-energize the enclosure.        16. Park and drop each applicable elbow to a portable feed-thru and/or standoff bushing        17. Remove the ground wire.and, after removing the mounting plate from the enclosure at step 2 above,        18. Disassemble nuts, bolts, lock washers and junction straps from the junction and discard the old junction.        
In the manufacture of a rigidly bolted junction mounting plate there are additional steps required as well as additional components. For instance, it is necessary to separately produce parking stands, precisely locate on the mounting plate and weld these parking stands to the mounting plate after the mounting plate is cut and formed in a die. Additionally, it is also necessary to separately provide the ground wire connection by welding a threaded insert to a front portion of the mounting plate.
Thus, there is a great need to minimize the time and effort required to install and/or maintain a pad mount electrical enclosure and to minimize the number of components required. There is also a need to minimise the cost and number of components required for the manufacture of a mounting plate.
It is also known to provide a drip-in type mounting plate which has a bottom flange received in a slotted rail and a curled over top flange received over a top rail, these rails mounted to the back panel of the enclosure. The drop-in mounting plate usually has a single threaded insert welded to the mounting plate adjacent each rail with a threaded fastener disposed therethrough for retaining the mounting plate to the rails. For instance, see the U.S. Pat. No. 4,246,436 issued on 20 Jan. 1981 to Hoffman, et al., these drop in type mounting plates used in the CW200 Series Primary Pedestal or the CW 300 Series Sectionalizing Enclosures manufactured by Maysteel, LLC, N89 W14700 Patrita Drive, Menomonee Falls, Wis. 53052 or the MEH Sectionalizing Enclosures manufactured by ABB Group, 501 Merritt 7, Norwalk, Conn., 06851, USA Headquarters or Primary Sectionalizing Enclosures manufactured by Barfield Mfg. Co., 621 Park Tower Drive, Manchester, Tenn. 37355. At assembly of junctions to a drop-in type mounting plate, the following steps are required:                1. Loosen the threaded fasteners disposed in the mounting plate to release the mounting plate from the enclosure.        2. Remove the drop-in type mounting plate from the enclosure.        3. Assemble junction straps to the junction.        4. Assemble lock washers to mounting bolts.        5. Hold the junction in place on the mounting plate while holding the mounting plate separate from the enclosure.        6. Install mounting bolts with lock washers in turn onto the junction straps and install nuts on the mounting bolts.        7. Tighten all nuts on the junction mounting bolts.        8. Install assembled junction mounting plate to enclosure.        9. Tighten fasteners to fasten the mounting plate to the enclosure.        10. Install ground wire to the threaded insert on the mounting plate.        11. Install ground wire to the enclosure.        12. Install elbows and cables to junctions.        13. Energize the junctions in the enclosure.        
Only one step is removed versus the rigidly bolted mounting plate which still is a lengthy and difficult procedure requiring the line person to hold onto the ten pound mounting plate while assembling components thereto. As with a rigidly bolted mounting plate, removal and reinstallation of junctions to a drop-in type mounting plate also requires the additional steps of prior to step 1 above though step 11 is omitted:                14. De-energize the enclosure.        15. Park and drop each applicable elbow to a portable feed-thru and/or standoff bushing.        16. Remove the mounting plate ground wire.and, between steps 2 and 3 above,        17. Disassemble nuts, bolts, lock washers and junction straps from the junction and discard the old junction.        
In addition to the additional steps required as well as additional components necessary to manufacture a rigidly bolted mounting plate there are two more components required for manufacture of a drop-in type mounting plate. For instance, it is necessary to separately provide the fasteners to secure the drop-in mounting plate to the enclosure and additional operations of welding these fasteners to the flanges of the mounting plate.
It is readily apparent that it is desirable to minimise the amount of labor, number of components as well as the time required to install, replace or maintain a grade level enclosure and to reduce the number of steps and components required for manufacture of a mounting plate.